Hermetically sealed distribution transformer



Feb. 1, 1966 R. F. SCHRADER ETAL 3,233,193

HERMETICALLY SEALED DISTRIBUTION TRANSFORMER 2 Sheets-Sheet 1 Filed Aug.5, 1964 d n 0 5 mm W. 1 n wm wmw 2M6 Feb. 1, 1966 R. F. SCHRADER ETAL3,233,198

HERMETICALLY SEALED DISTRIBUTION TRANSFORMER 2 Sheets-Sheet 2 Filed Aug.5, 1964 ,1 United States Patent-O 3,233,198 .HERMETICALLY SEALEDDISTRIBUTION TRANSFURMER Roger F. Schrader, Wilmer H. Airgood, andGordon C. Nonken, all of Pittsfield, Mass, assignors to General ElectricCompany, a corporation of New York Filed Aug. 3, 1964, Ser. No. 387,12512 Claims. (CL 33694) This invention relates to distributiontransformers and, more particularly, to hermetically sealed distributiontransformers.

As is well known to those skilled in the transformer art, manyfailuresof distribution transformers, in use, -are due to the entranceof moisture and other contaminants into the sealed interior of thetransformer. Many 'present-day transformers comprise a tank member intowhich is mounted the core and coil unit. A quantity of dielectric liquidis then placedin the tank and a cover mounted on the top thereof. Thecover is usually sealed 'to the tank with some type of gasket by meansof clampjing bands or clamping bolts. Also, as is well known, hand holesare usually provided in the coverto allow inspectionof the transformerinterior without removing -the cover. Of course, the hand holes are alsoprovidedwith covers which are sealed to the main cover by a gasket andclamping bolts. While tankcover's and hand hole covers may beadequatelytested duringproduction for effective sealing, there is nopractical means to test for effective sealing of these covers once thecustomer has removed either cover for inspection of the transformer. Asa consequence, many transformers presently in use are not properlysealed. The lack of proper sealing allows moisture and othercontaminants to enter, shortening the effective life of the transformer.The moisture and contaminants, in general, weaken the dielectricmaterial of the transformer, suchthat the trans- ,former will fail whensubjected to an otherwise harml'ess over"voltage. Ofcourse, as is wellknown, the

effect of moisture and other contaminants on the dielectric inaterialofthe transformer causes progressive Weakening of such dielectricmater1al;

Another well-recognized problem in todays distribution transformer isthe air pocket in the top of the transformer tanks As is wellunderstood, the transformer tank is usually only filled part way withdielectric liquid having an air pocket in the upper portion of thetransformer tank. This air pocket allows for the eX pansionof the liquiddue to temperature changes during the operation of the transformer.However, the air pocket requires'that the transformer be constantlymaintained in an upright position to prevent trapping of air bubbles inthe electrical coil. As is well known, air

bubbles in the coil structure will often cause the transformer to failduring service.

It is therefore one object of this invention to provide an improveddistribution transformer which is hermetically sealed.

size and lighter in weight than conventional transformers ofequivalentrating. In carrying out this invention in one preferred form, a novel,hermetically sealed, distribution transformer is provided, having asubstantially form-fitting central housing which surrounds four sides ofthe transformer core spective bushings.

16. 45 :vided on the central portion 12, while a hanger bracket3,233,198 Patented Feb. I, 1966 and coil unit. A pair of cooling flangesare hermetically attached to opposite sides of the central housing,closely conforming to the shape of the core and coil unit, therebyforming a hermetically sealed enclosure. High voltage bushings and lowvoltage bushings are hermetically sealed to the hermetically sealedenclosure. High and low voltage winding leads are internally connectedto their re- The interior of the enclosure is completely filled with adielectric cooling liquid.

The invention which is sought to be protected will be clearly pointedout and distinctly claimed in the claims appended hereto. However, it isbelieved that this invention and the manner in which its objects andadvantages are obtained, as well as other objects and advantagesthereof, will be more fully understood from the following detaileddescription of a preferred embodiment thereof, especially whenconsidered in the'light of the accompanying drawings, in which:

FIGURE 1 is a perspective view of a hermetically sealed transformeraccording to a preferred form of the invention;

FIGURE 2 is a side view of the hermetically sealed transformer of FIG.1; and

FIGURE 3 is an exploded perspective view of the hermetically sealedtransformer of FIG. 1 showing a preferred form of construction thereof.

Reference will now be made to the drawings for a detailed description ofthe present preferred embodiment of this invention, in accordance withthe patent statutes.

Like numerals will be used to indicate like parts throughout the variousviews thereof.

Referring first to FIG. 1 of the drawings, there is shown a perspectiveview of a preferred embodiment of the hermetically sealed transformer ofthis invention. As can be seen from FIG. 1, the hermetically sealedtransformer 10 comprises a substantially four-sided, central portion 12having flange members 14 and 16 secured to opposite sides of the centralportion 12. As can be seen the flanges 14 and 16 are of greater extentthan "the central portion 12. A pair of high voltage bushings 18 and 20are shown as mounted on flange 14, while a low voltage bushing 22 may beseen connected to flange In the usual manner, a lifting eye 24 may bepro- 26 may also be provided to facilitate the mounting of thetransformer 10 on a pole in a manner Well understood by those skilled inthis art.

FIGURE 2 shows in greaterdetail the internal construction of thetransformer 10, while FIG. 3 shows, in

perspective view, the manner of constructing the preferred embodiment ofthe transformer. Referring first to FIG. 2 of the drawings, it may beseen that the transformer 10 is provided with a pair of filling plugs 28and 30, one plug being on flange 16 while the other plug is on flange14. As will be well understood after the transformer 10 is completelyassembled and hermetically sealed, a vacuum may "be pulled on one plug,for example, filling plug 28 while cooling dielectric liquid is fed intothe interior of transformer 10 by means of the other filling plug 30. Inthis manner, as will be well understooththe entire interior oftransformer 10 may become completely filled with the dielectric coolingliquid, such that no trapped air will be contained within transformer10. Thus, as will be readily understood, the transformer 10 may beshipped in any convenient position, such as on its side orany othermanner. The elimination of the air pocket also eliminates the need forthe transformer to be constantly maintained in an upright position.Further, as will be appreciated the transformer 10 may be readilymounted on a pole while the .pole is lying on the ground; thus, enablingsimpler mounting of the hermetically sealed transformer of thisinvention without requiring dangerous work at the top coil member.

of a pole. A ground clamp may be provided for transformer 10, such asground clamp 31 shown as connected to flange 14.

Considering now FIG. 3 of the drawing, it may be seen that the centralhousing portion 12 is substantially a foursided, rectangularly shapedmember in which is mounted the core and coil unit 32. Core and coil unit32 may be firmly secured within housing 12, in any desired manner. Aswill be understood core and coil unit 32 will generally comprise a coremember of oriented magnetic strip steel and will have mounted thereon atleast one preformed Of course, it will be apparent that any conventionalcore and coil unit may be utilized in the transformer of this invention.As can be seen from FIG. 3, the central housing 12 conformssubstantially to the shape of the core and coil unit 32, beingsubstantially form-fitting with reference to the core and coil unit. Thehigh voltage leads 34 and 35 may be brought out from the coil of coreand coil member 32 through an insulated high voltage lead support 38 asshown. In a similar manner, the low voltage leads may be brought outfrom the coil of the core and coil unit 32.

Cooling flanges 14 and 16 are provided as hereinbefore specified onopposite ends of the central housing 12. As may be seen from FIG. 3 thehigh voltage flange 14 comprises an inner flange 4t) and an outer flangemember 42. The inner flange member 40 is provided with a substantiallyrectangular-shaped opening which corresponds to the outer shape of thecentral housing 12 and is hermetically sealed to housing 12, preferablyby means of Welding. The outer member 42 is provided with a pod-shapedportion, as shown, into which will fit the outer portion of the core andcoil unit in the manner specifically indicated by FIG. 2 of thedrawings. The outer member 42 is attached to the inner flange 40hermetically such as, for example, by welding along the entire outerseam of the two flanges such as is indicated at 44 in FIGS. 1 and 2.High voltage bushing members 18 and 20 are provided on 'the pod ofmember 42 in the manner indicated. Preferably the high voltage bushingswill be cast of an epoxy resin material having integral studs, althoughit will be understood that they may be molded or cast with a cable leadextending therethrough. Preferably a metal mounting flange, such as 46or 48, may be provided on the bushings, for example, being spun over theepoxy with a sealant provided and will be welded to the pod to provide ahermetic seal between the bushing and member 42. The high voltage leads34 and 36 will be connected internally to the integral stud or cablelead of the bushings 18 and 20 to provide the high voltage connection.It will be understood that other types of bushings may be used, ifdesired. The basic requirement is that each bushing be hermeticallysealed to the housing. The number of bushings required will, of course,depend on the specific transformer.

The other flange 16, in a similar manner, is provided with the innerflange portion 50 and the outer flange 52. Outer flange 52 is providedwith a pod-shaped portion as indicated, to conform to the oppositeportion of the core and coil unit. In the same manner as flange 14,portion 50 of flange 16 has a central opening conforming to the shape ofthe central housing 12 and is hermetically sealed thereto such as, forexample, by welding. The outer flange member 52 is hermetically sealedto inner flange 59 such as, for example, by welding as is indicated at'54 in FIGS. 1 and 2. The low voltage leads are brought to the lowvoltage bushings generally indicated by the numeral 22 in FIG. 3. In thepreferred embodiment the low voltage bushings 22 are also cast of epoxyresin having an integral stud and may be cast directly'on a flange 50,if desired, thus providing the desired hermetical seal to the coolingflange 50. The integral stud cast in the bushing 22 will be connected tothe low voltage leads internally in .a manner well understood by thoseskilled in the art. Again, it will be understood that any type ofbushing m y be used, it only being necessary that such bushing behermetically sealed to the transformer. The number of bushings requiredwill depend on the transformer.

Of course, if desired the lifting eye 24 may be welded to the centralportion 12 and the hanger bracket may be welded to the side of thecentral portion particularly in the manner indicated in FIGS. 1 and 2 ofthe drawings. After the transformer has been completely assembled, itwill be understood that each opening, with the exception of the fillingplugs 28 and 30, will be hermetically sealed, preferably by means ofwelding. The filling plugs 28 and 30 will be utilized to completely fillthe interior of the transformer 10 with a dielectric cooling liquid andthen each of the plugs may be hermetically sealed. For example, they maybe welded closed or they may be provided with screw fittings which willcompletely seal the openings. In this manner there will be provided ahermetically sealed transformer 10 with the entire interior of thetransformer completely filled with a dielectric cooling liquid. Ofcourse, as will be understood, due to the form-fitting of the centralportion 12 and the cooling flanges 1 4 and 16 the hermetically sealedtransformer 10 will be substantially smaller and lighter thanconventional transformers of similar ratings.

If it is a desirable to provide for small expansion of the liquiddielectric which completely fills the interior of the transformer 10 theflanges 14 and 16 may be made of tthin gauge steel which will allow themto fiex under the pressure of the expanding liquid within transformer10. Thus the small expansion of the liquid may be readily contained bythe flexing of the flanges 14 and 16 without the necessity for any airpockets within the transformer.

From the above it will be apparent that there has been provided ahermetically sealed distribution transformer which will fill all of theobjects hereinbefore set forth.

Of course, it will be readily apparent to those skilled in the art thatthe specific details of construction andthe specific size and shapes ofthe various portions of the transformer while presently preferred arenot required. It will be apparent to those skilled in the art that manyvariations and modifications may be made of the single embodimentdisclosed. For example, it will be obvious that the high and low voltagebushings .could be mounted on the same cooling flange, if desired. Theycould also be hermetically sealed to the central portion. Of course, thecooling flanges could be the same size as the central portion,especially for low rated transformers. It is intended to include allsuch modifications and variations within the scope of the invention asit is defined in the appended claims.

What is claimed as new and which it is desired to secure by LettersPatent of the United States is:

1. A hermetically sealed distribution transformer comprising, incombination, a rectangular-shaped housing open at opposite ends, a coreand coil unit having high and low voltage leads secured within saidhousing, a pair of cooling flanges of greater extent than said housing,said cooling flanges being welded to said open opposite ends of saidhousing to form a hermetically sealed enclosure including said flanges,at least one high voltage bushing hermetically sealed to one of saidpair of cooling flanges and internally connected to said high voltageleads, low

voltage bushings hermetically sealed to the other of said coolingflanges being welded to said open opposite ends of said housing to forma hermetically sealed enclosure including said flanges, at least onehigh voltage bushing hermetically sealed to one of said pair of coolingflanges and internally connected to said high voltage leads, loW voltagebushings hermetically sealed to one of said pair of cooling flanges andinternally connected to said low voltage leads, the interior of saidhermetically sealed enclosure being completely filled with a dielectriccooling liquid.

3. A hermetically sealed distribution transformer comprising, incombination, a rectangular-shaped housing open at opposite ends, a coreand coil unit having high and low voltage leads secured within saidhousing, a pair of cooling flanges of greater extent than said housing,said cooling flanges being welded to said open opposite ends of saidhousing to form a hermetically sealed enclosure including said flanges,at least one high voltage bushing and low voltage bushings hermeticallysealed to said enclosure, said bushings being internally connected tosaid high and low voltage leads, the interior of said hermeticallysealed enclosure being completely filled with a dielectric coolingliquid.

4. A hermetically sealed transformer comprising, in combination, a coreand coil unit, said core and coil unit having high voltage and lowvoltage leads, a central housing portion surrounding and containing saidcore and coil unit on four sides, a pair of cooling flanges of greaterextent than said central portion, said cooling flanges being welded tosaid central portion and completing a hermetic enclosure including saidflanges about said core and coil unit, at least one high voltage bushinghermetically sealed to one of said pair of cooling flan es and beinginternally connected to said high voltage leads, low voltage bushingshermetically sealed to the other of said pair of cooling flanges andinternally connected to said low voltage leads, filling plugs beingprovided in said cooling flanges and the interior of said hermeticenclosure being completely filled with a dielectric cooling liquid.

5. A hermetically sealed transformer comprising, in combination, a coreand coil unit, said core and coil unit having high voltage and lowvoltage leads, a central housing portion surrounding and containing saidcore and coil unit on four sides, a pair of cooling flanges of greaterextent than said central portion, said cooling flanges being welded tosaid central portion and completing a hermetic enclosure including saidflanges about said core and coil unit, at least one high voltage bushingand low voltage bushings hermetically sealed to said enclosure, saidbushings being internally connected to said high and low voltage leads,filling plugs provided in said enclosure and the interior of saidhermetic enclosure being completely filled With a dielectric coolingliquid.

6. A heremetically sealed transformer comprising, in combination, a coreand coil unit, said core and coil unit having high voltage and lowvoltage leads, a central housing portion surrounding and containing saidcore and coil unit on four sides, a pair of cooling flanges of greaterextent than said central portion, said cooling flanges being Welded tosaid central portion and completing a hermetic enclosure including saidflanges about said core and coil unit, high and low voltage bushingshermetically sealed to at least one of said pair of cooling flanges andbeing internally connected to said high and low voltage leads, fillingplugs provided in at least one of said cooling flanges and the interiorof said hermetic enclosure being completely filled with a dielectriccooling liquid.

7. A hermetically sealed distribution transformer comprising, incombination, a substantially rectangular-shaped housing open at oppositeends, a core and coil unit having high voltage and low voltage leadssecured within said housing, said housing being substantiallyform-fitting with respect to said core and coil unit, a pair of coolingflanges of greater extent than said housing, said cooling flanges beingwelded to said open opposite ends of said housing to form a hermeticallysealed enclosure including said flanges, each of said cooling flangesbeing provided with a pod portion to substantially conform to the shapeof said core and coil unit, at least one high voltage bushinghermetically sealed to one of said pair of cooling flanges andinternally connected to said high voltage leads, low voltage bushingshermetically sealed to the other of said pair of cooling flanges andinternally connected to said low voltage leads, the interior of saidhermetically sealed enclosure completely filled with a dielectriccooling fluid.

8. A hermetically sealed distribution transformer as claimed in claim 7in which said cooling flanges are made of thin gauge metal to allow forflexing during the expansion of said cooling fluid within saidtransformer.

9. A hermetically sealed distribution transformer comprising, incombination, a substantially rectangular-shaped housing open at oppositeends, a core and coil unit having high voltage and low voltage leadssecured within said housing, said housing being substantiallyform-fitting with respect to said core and coil unit, a pair of coolingflanges of greater extent than said housing, said cooling flanges beingwelded to said open opposite ends of said housing to form a hermeticallysealed enclosure including said flanges, each of said cooling flangesbeing provided with a pod portion to substantially conform to the shapeof said core and coil unit, high and low voltage bus rings hermeticallysealed to said hermetically sealed enclosure and internally connected tosaid high and low voltage leads, he interior of said hermetically sealedenclosure completely filled with a dielectric cooling fluid.

10. A hermetically sealed distribution transformer comprising, incombination, a core and coil unit, high and low voltage leads extendingfrom the coil of said core and coil unit, a hermetic enclosure aboutsaid core and coil unit, said hermetic enclosure comprising a centralportion surrounding four sides of said core and coil unit and flangemembers on opposite sides of said central portion of greater extent thansaid central portion and hermetically sealed thereto to complete saidhermetic enclosure including said flanges, high and low voltage bushingshermetically sealed to said enclosure and internally connected to saidhigh and low voltage leads, and the interior of said hermetic enclosurecompletely filled with a dielectric fluid.

11. A hermetically sealed transformer as claimed in claim 10 in whichsaid flange members are made of thin gauge metal which will flex tocontain expansion of said dielectric fluid.

12. A hermetically sealed distribution transformer comprising, incombination, a substantially rectangular shaped housing open at oppositeends, a core and coil unit having high voltage and low voltage leadssecured Within said housing, said housing being substantiallyform-fitting with respect to said core and coil unit, a pair of coolingflanges of greater extent than said housing, said cooling flanges beingwelded to said open opposite ends of said housing to form a hermeticallysealed enclosure including said flanges, each of said cooling flangesbeing provided with a pod portion to substantially conform to the shapeof said core and coil unit, high and low voltage bushings, hermeticallysealed to said hermetically sealed enclosure and internally connected tosaid high and low voltage leads, at least one filling plug provided insaid sealed enclosure, the interior of said hermetically sealed encosurecompletely filled with a dielectric cooling fluid.

No references cited.

ROBERT K. SCHAEFER, Primary Examiner.

3. A HERMETICALLY SEALED DISTRIBUTION TRANSFORMER COMPRISING, INCOMBINATION, A RECTANGULAR-SHAPED HOUSING OPEN AT OPPOSITE ENDS, A COREAND COIL UNIT HAVING HIGH AND LOW VOLTAGE LEADS SECURED WITHIN SAIDHOUSING, A PAIR OF COOLING FLANGES OF GREATER EXTENT THAN SAID HOUSING,SAID COOLING FLANGES BEING WELDED TO SAID OPEN OPPOSITE ENDS OF SAIDHOUSING TO FORM A HERMETICALLY SEALED ENCLOSURE INCLUDING SAID FLANGES,AT LEAST ONE HIGH VOLTAGE BUSHING AND LOW VOLTAGE BUSHINGS HERMETICALLYSEALED TO SAID ENCLOSURE, SAID BUSHINGS BEING INTERNALLY CONNECTED TOSAID HIGH AND LOW VOLTAGE LEADS, THE INTERIOR OF SAID HERMETICALLYSEALED ENCLOSURE BEING COMPLETELY FILLED WITH A DIELECTRIC COOLINGLIQUID.